分离CO2的促进传递膜

促进传递膜在分离机制上有别于普通分离膜，由于透过组分与膜中载体之间特异性的可逆反应使其性能优异．文章综述了国内外近年来在分离CO2促进传递膜方面的研究进展，特别介绍了本课题组在固定载体膜方面的研究结果，选择、研制固定工体膜材料所遵循的基本思路，以及对固定地体膜内传递机理所做的一些新探索．     

超临界CO2方法制备环氧树脂/纳米介孔MCM-41复合材料

采用超临界方法先将环氧树脂低聚物引入介孔MCM-41的一维孔道内,再与基体溶液共混,制备出环氧树脂／MCM-41纳米复合材料．研究了复合材料的拉伸性能与填充复合颗粒含量的关系．结果表明,超临界的方法确实可将环氧树脂低聚物分子链引入到MCM-41的孔道,并占据孔道的绝大多数空间．环氧基团进入介孔的孔道中并使孔口处的环氧基团与基体环氧产生了较强的界面相互作用,增加了两者的相容性．填充含量较低的复合颗粒就能提高复合材料的拉伸性能．     

Recent Advances in Direct Synthesis of Value‐Added Aromatic Chemicals from Syngas by Cascade Reactions over Bifunctional Catalysts

Value‐added aromatic monomers such as benzene, toluene, and xylenes (BTX) are very important building‐block chemicals for the production of plastics, polymers, solvents, pesticides, dyes, and adhesives. Syngas‐to‐aromatics (STA) is a very promising approach for the synthesis of aromatic monomers, and is catalyzed via bifunctional catalysts in a single reactor, wherein methanol/dimethyl ether and/or olefins intermediates formed from syngas on metal components are converted into aromatic monomers exclusively on the HZSM‐5 by cascade reactions. Since an optimal Fischer–Tropsch synthesis (FTS) temperature of Fe‐based catalysts is very close to an aromatization temperature of HZSM‐5, Fe‐based catalysts have been frequently used/modified for the synthesis of aromatic monomers from hydrogenation of carbon oxides (CO and CO₂). The nature of metal components and amounts of Brönsted acid sites on HZSM‐5, and their mesoporosity and intimacy, significantly alter the selectivity for aromatics by tuning BTX distibution and catalyst stability. Although many developments have been achieved regarding the STA process in recent years, no reviews have been published in this flourishing research area over the last two decades. Here, the recent advances and forthcoming challenges in the progress of syngas (CO+H₂) chemistry and hydrogenation of CO₂ toward the value‐added aromatic monomers through cascade reactions are highlighted.     

超临界CO_2增强聚合物加工的研究与应用进展

对超临界CO2环境中聚合物加工方法的研究、应用现状与进展进行了综述。基于SC-CO2对聚合物的增塑作用,可开发出许多相关用途,如聚合物改性、聚合物共混、聚合物复合材料、多孔微泡沫材料、微粒化以及聚合物浸渍/灌注/插嵌等。在对研究现状和结果进行梳理总结后,认为SC-CO2对聚合物加工过程的增强作用机理可归结为:SC-CO2对聚合物的溶胀,导致增塑,进而降低了聚合物的玻璃化温度、黏度、表面张力,增强了小分子化合物在聚合基质中的扩散系数。此外,CO2作为绿色溶剂,是有机溶剂的良好替代品,因此具有广阔的应用前景。     

Ultrasound-induced capping of polystyrene on TiO2 nanoparticles by precipitation with compressed CO2 as antisolvent

In this work, a route for the synthesis of inorganic/polymer core/shell composite nanoparticles was proposed, which can be called the antisolvent-ultrasound method. Compressed CO2 was used as antisolvent to precipitate the polymer from its solution dispersed with inorganic nanoparticles, during which ultrasonic irradiation was used to induce the coating of precipitated polymers on the surfaces of the inorganic nanoparticles. TiO2/polystyrene (PS) core/shell nanocomposites have been successfully prepared using this method. The transmission electronic micrographs (TEM) of the obtained nanocomposites show that the TiO2 nanoparticles are coated by the PS shells, of which the thickness can be tuned by the pressure of CO2. The phase structure, absorption properties, and thermal stability of the composite were characterized by X-ray diffraction (XRD), UV-vis spectra, and thermogravimetry, respectively. The results of X-ray photoelectron spectra (XPS) indicate the formation of a strong interaction between PS and TiO2 nanoparticles in the resultant products. This method has some potential advantages for applications and may be easily applied to the preparation of a range of inorganic/polymer core/shell composite nanoparticles.     

Plasma polymerization of iron pentacarbonyl with C2 hydrocarbons

Iron-containing plasma polymers are deposited from a plasma using iron pentacarbonyl (Fe(CO)₅) plus C₂ hydrocarbons as comonomers and are characterized using a variety of techniques. The plasma polymers are found to contain high proportions of highly dispersed iron oxide as well as lesser quantities of carboxylate and/or ketonate ions and aldehydic and/or ketonic groups. By decreasing the energy per unit mass W/FM part of the iron is deposited in a lower oxidation state complexed to CO and is soluble in organic solvents. The effects of hydrocarbon saturation and of the ratio of hydrocarbon to Fe(CO)₅ are also described and a comparison is made with the product deposited when only Fe(CO)₅ (or Fe(CO)₅ plus H₂) is used as the monomer.     

25th Anniversary Article: Isoindigo‐Based Polymers and Small Molecules for Bulk Heterojunction Solar Cells and Field Effect Transistors

Driven by the potential advantages and promising applications of organic solar cells, donor‐acceptor (D‐A) polymers have been intensively investigated in the past years. One of the strong electron‐withdrawing groups that were widely used as acceptors for the construction of D‐A polymers for applications in polymer solar cells and FETs is isoindigo. The isoindigo‐based polymer solar cells have reached efficiencies up to ～7% and hole mobilities as high as 3.62 cm² V^?1 s^?1 have been realized by FETs based on isoindigo polymers. Over one hundred isoindigo‐based small molecules and polymers have been developed in only three years. This review is an attempt to summarize the structures and properties of the isoindigo‐based polymers and small molecules that have been reported in the literature since their inception in 2010. Focus has been given only to the syntheses and device performances of those polymers and small molecules that were designed for use in solar cells and FETs. Attempt has been made to deduce structure‐property relationships that would guide the design of isoindigo‐based materials. It is expected that this review will present useful guidelines for the design of efficient isoindigo‐based materials for applications in solar cells and FETs.     

Improvements in polymer characterization by size-exclusion chromatography and liquid chromatography at the critical condition by using enhanced-fluidity liquid mobile phases with packed capillary columns

Microscale chromatography has found numerous applications in liquid chromatography. The combination of enhanced-fluidity liquid mobile phases with packed-capillary LC is evaluated for polymer characterization using size-exclusion chromatography (SEC) and liquid chromatography at the critical condition (LCCC) phase. Separations of polystyrene polymers and copolymers are completed using liquid chromatography at the critical condition. The critical conditions of polystyrene polymers were approached by changing the concentration of CO(2) in the mixture combined with temperature and pressure variation. Because the solvent strength of enhanced-fluidity liquid mixtures is affected by temperature and pressure variation, the solvent strength could be fine-tuned to accurately find the critical condition. Long packed capillaries could be used in this application because the enhanced-fluidity mobile phases have low viscosities. High efficiencies resulted. The performance of packed-capillary and analytical-scale analytical columns containing the same packing material was compared for a challenging separation at the critical condition.     

导电聚合物在纳米太阳能电池中的应用研究

导电聚合物以其特殊的性质及种种优点而越来越广泛地应用于光电化学太阳能电池,文中主要介绍了导电聚合物作为全固态太阳能电池的电解质以及作为纳米光电化学太阳能电池敏化剂的应用研究。     

含1,3,4-噻二唑环聚合物的合成及应用研究进展

含1,3,4-噻二唑环聚合物作为一类新型功能性的芳香杂环聚合物,由于其独特的储能性能、电催化活性、富电子特性而备受关注。近20年来对于含1,3,4-噻二唑环聚合物的研究从未间断,主要集中在材料的电化学合成和结构表征及其在可充电锂电池正极材料、生物化学传感器、临床诊断和药理学等领域的应用。电化学合成的方法有利于制备厚度可控的自支撑膜和对电极进行修饰,缺陷是造成电解液污染、成本高以及不适合规模化生产。研究者们尝试使用化学氧化聚合的方法来合成含1,3,4-噻二唑环聚合物,但除了2,5-二巯基-1,3,4-噻二唑聚合物可通过此方法成功合成外,主要得到的是一些配合物或配位聚合物。采用绿色的规模化的制备工艺来合成含1,3,4-噻二唑环聚合物是大势所趋。含1,3,4-噻二唑环聚合物的结构表征由于受到溶解性的限制,表征手段主要为X射线光电子能谱和红外(拉曼)光谱。2,5-二巯基-1,3,4-噻二唑聚合物由于具有高能量密度和高比容量而在二次锂电池正极材料的应用方面受到研究者们的青睐,但存在着充放电缓慢和电容量衰减快等缺陷。基于含1,3,4-噻二唑环聚合物修饰电极构建的传感器可高灵敏且高选择性地探测许多生物相关分子,但电极的稳定性有待改善。在所有的1,3,4-噻二唑环聚合物中,聚2-氨基-1,3,4-噻二唑(PAT)、聚5-氨基-1,3,4-噻二唑-2-硫醇或5-氨基-2-巯基-1,3,4-噻二唑(PAMT)以及聚2,5-二巯基-1,3,4-噻二唑(PBT)已通过电化学方法合成;PBT也在绿色的合成条件下采用化学氧化合成法合成得到,为其他1,3,4-噻二唑环聚合物的合成提供了借鉴,本课题组也通过化学氧化聚合法制备了PAT、PAMT和聚2-巯基-1,3,4-噻二唑(PTT)三类聚合物。目前,PBT作为二次锂电池正极材料研究得最多,其理论比容量高达362mAh/g,研究者们将PBT与聚吡咯、聚苯胺或水溶性磺化石墨烯等导电聚合物制成复合电极,进一步提高比容量和电极的稳定性并且加速充放电过程。基于含1,3,4-噻二唑环聚合物修饰电极构建的传感器在探测天然产物有效成分的含量、人和哺乳动物血液和体液或药品注射液中药物或代谢产物的含量、中药材或食品中的农药残留量以及水溶液中的重金属离子含量等方面取得了丰硕的成果;而将1,3,4-噻二唑环聚合物与全氟磺酸粘合剂、多壁碳纳米管复合可减少聚合物流失,从而起到增强电极稳定性和延长使用寿命的作用。本文归纳了1,3,4-噻二唑环聚合物研究进展,分别对1,3,4-噻二唑环聚合物的合成、结构表征途径及其应用等进行了介绍,分析了1,3,4-噻二唑环聚合物的研究中面临的问题并展望了其应用前景,以期为1,3,4-噻二唑环聚合物的制备工艺和功能拓展提供参考。     

Adsorption of conditioning polymers on solid substrates with different charge density

The adsorption processes of polymers that belong to two different families (neutral hydrophilic polymers and cationic polysaccharide polymers) onto solid surfaces with different charge density have been studied using dissipative quartz crystal microbalance (D-QCM) and ellipsometry. The polymers studied are very frequently used in the cosmetic industry as conditioning agents. The adsorption kinetics of the polymers involves at least two steps. The total adsorbed amount depends on the charge density of the surface for both types of polymers. The comparison of the adsorbed mass on each layer obtained from D-QCM and from ellipsometry has allowed calculating the water content of the layers that reaches high values for the polymers studied. The analysis of D-QCM results also provided information about the shear modulus of the layers, whose values have been found to be typical of a rubber-like polymer system. The main driving force of the adsorption was found to be the energy of the interactions between chains and surface.     

Polymer nanosieve membranes for CO2-capture applications

Microporous organic polymers (MOPs) are of potential significance for gas storage, gas separation and low-dielectric applications. Among many approaches for obtaining such materials, solution-processable MOPs derived from rigid and contorted macromolecular structures are promising because of their excellent mass transport and mass exchange capability. Here we show a class of amorphous MOP, prepared by [2+3] cycloaddition modification of a polymer containing an aromatic nitrile group with an azide compound, showing super-permeable characteristics and outstanding CO(2) separation performance, even under polymer plasticization conditions such as CO(2)/light gas mixtures. This unprecedented result arises from the introduction of tetrazole groups into highly microporous polymeric frameworks, leading to more favourable CO(2) sorption with superior affinity in gas mixtures, and selective CO(2) transport by presorbed CO(2) molecules that limit access by other light gas molecules. This strategy provides a direction in the design of MOP membrane materials for economic CO(2) capture processes.     

Nonintrusive optical measurements of aircraft engine exhaust emissions and comparison with standard intrusive techniques

Nonintrusive systems for the measurement on test rigs of aeroengine exhaust emissions required for engine certification (CO, NO(x), total unburned hydrocarbon, and smoke), together with CO(2) and temperature have been developed. These results have been compared with current certified intrusive measurements on an engine test. A spectroscopic database and data-analysis software has been developed to enable Fourier-transform Infrared measurement of concentrations of molecular species. CO(2), CO, and NO data showed agreement with intrusive techniques of approximately ?30%. A narrow-band spectroscopic device was used to measure CO(2) (with deviations of less than ?10% from the intrusive measurement), whereas laser-induced incandescence was used to measure particles. Future improvements to allow for the commercial use of the nonintrusive systems have been identified and the methods are applicable to any measurement of combustion emissions.     

Recent advances in shape memory polymers and composites: a review

Shape memory polymers (SMPs) belong to a class of smart polymers, which have drawn considerable research interest in last few years because of their applications in microelectromechanical systems, actuators, for self healing and health monitoring purposes, and in biomedical devices. Like in other fields of applications, SMP materials have been proved to be suitable substitutes to metallic ones because of their flexibility, biocompatibility and wide scope of modifications. The shape memory properties of SMPs polymers might surpass those of shape memory metallic alloys (SMAs). In addition to block copolymers, polymers blends and interpenetrating network structured SMP systems have been developed. The present review mainly highlights the recent progress in synthesis, characterization, evaluation, and proposed applications of SMPs and related composites.     

Thermal behaviour of polymeric Langmuir-Blodgett multilayers

Langmuir-Blodgett multilayers of hydrocarbon and fluorocarbon polymers with hydrophilic spacer, lipid-polyelectrolyte complexes and mesogenic polymers have been prepared. The thermal behaviour of the multilayers was studied by small angle X-ray scattering, IR and UV—visible spectroscopy. Good thermal stabilities were found for the various classes of polymers. In addition, for both complexed multilayers and mesogenic polymer films, reorientation processes were observed.     

High-temperature polymers for adhesive and composite applications

Abstract

The aerospace industry is currently making extensive use of both structural adhesives and composite materials in aircraft and space vehicle construction. Within the past decade, there has been a growing requirement for adhesives and composites capable of withstanding temperatures in excess of 150°C for both short- and long-term applications. Although polymers offering such capabilities have been commercially available for many years, in numerous cases adverse processing characteristics have severely restricted their acceptance. As a result, substantial efforts have been made to develop high temperature resistant polymers having considerably improved processing characteristics. In this paper, a critical assessment is given of the use of high-temperature polymers in both adhesive and composite applications with particular emphasis on some of the newer, more easily processed types which are, or will probably be, commercially acceptable.

MST/659     

Polymer micromachining for micro- and nanophotonics

Polymeric materials have been used in the fabrication of many high-performance, low cost photonic devices for optical communications, interconnects and sensors. The paper presents two low cost techniques for polymer based photonic components fabrication, such as waveguides, diffractive optical elements and optical modulators.We used both photopatternable (metal doped PVA) and nonphotopatternable polymers (PMMA and silicone polymers).The photosensitivity and, in the same time, refractive index of the poly(vinyl-alcohol) were modified through the addition inorganic/organic materials. These new light-sensitive nanocomposites can be easily spin coated onto variety of semiconductor substrates, and directly patterned to obtain channel waveguides and photonic integrated circuits.For nonphotopatternable polymers, two types of molds have been used: grooves etched in silicon or in silicon dioxide and photoresist molds. Rib waveguides and tunable modulators, voltage actuated, have been obtained using these techniques.     

The containment of oil spills in porous media using xanthan/aluminum solutions, gelled by gaseous CO2 or by AlCl3 solutions

The gelation in situ of polymers may be a method for temporarily containing organic solvents and other petroleum derived products, which may enter the subsurface. In order to create gels that are neither toxic to humans nor to the ecosystem, we have investigated on the use of the biopolymer xanthan gum with aluminum as a crosslinking agent. Firstly we have considered xanthan/sodium aluminate solutions, which upon preparation are strongly basic and do not gel. The gelation takes place in acid solutions so that Al(III) ions are released, and is instantaneous. Therefore, a special technique must be used for generating the gel structure in situ. The un-gelled solution must be injected and an acid must be added afterwards. We have investigated on the gelling reaction induced by gaseous carbon dioxide, which is an acid gas. The insufflation of CO(2) above the solution generates a layer of gel whose thickness progressively increases as CO(2) diffuses in the polymer solution. Secondly we have investigated on the use of aluminum chloride as the source of Al(III) ions. Also in this case, due to the full availability of Al(III) ions, the gelling reaction would be instantaneous. Therefore, the solution of AlCl(3) must be added on the top of the xanthan solution after its injection. For both gelling systems we have studied both theoretically and experimentally the rate of formation of the gel layer which progressively thickens after the insufflation of CO(2) or after the addition of the AlCl(3) solution.     

Covalent-bonded graphyne polymers with high hardness

Eight covalent-bonded graphyne polymers have been proposed using the newly developed USPEX and CALYPSO methods based on the first-principle calculations. These polymers are energetically more favorable than the corresponding graphyne under ambient pressure, and seven of them are more stable than fullerene C₆₀, indicating their existence possibilities. The mechanical and dynamic stabilities of these crystal structures have been confirmed by calculating their elastic constants and phonon dispersion curves, respectively. The newly developed variable-cell nudged elastic band (VC-NEB) simulations show that the graphyne → polymer transformation exhibits lower energy barrier than the graphite → diamond transformation. Two of the graphyne polymers have been found to be superhard, and the others are hard materials. These graphyne polymers possess tunable electronic properties from metallic to semiconductive.     

A novel building block for donor-acceptor conjugated polymers containing perylene, poly(p-phenylenevinylene), and fullerene

A series of new polymers containing perylene, poly(p-phenylenevinylene) (PPV) and/or pendant fullerene units have been synthesized by Wittig condensation. All of the polymers were characterized by 1HNMR, FT-IR, and GPC. The optical properties of the polymers were studied by UV-vis and FL spectra. The cyclic voltammetry showed us a good candidate for a photoinduced electron-transfer system. And the photocurrent measurement revealed an interesting phenomenon that the photocurrent increased with the contents of the fullerene in the polymers increased.